1. Field of the Invention
The present invention relates to a gas cylinder for use in a table and a chair, for adjusting a height of a table and a chair, etc., and more particularly to a gas cylinder capable of increasing the size of a primary axis (spindle) for use in the gas cylinder, specifically increasing up and down movement width (stroke) of a spindle even at a status that the whole size of the gas cylinder is the same.
2. Background of the Related Art
A gas cylinder is an apparatus for use in an impulse buffering apparatus of an automobile, a table or a chair, for making a product installed on the gas cylinder more convenient by reducing impulse applied from the outside, or by applying restoring force in one direction. The gas cylinder according to the present invention does not exclude application to different usage such as an impulse buffering apparatus, but the gas cylinder more preferably applicable to a chair, will be described as an example.
The gas cylinder is an apparatus for exerting force in one direction the length of the cylinder increases, and in case that a user does not sit on a chair, the length of the cylinder increases by force extending in one direction. Also, in case that a user sits on a chair, extending force of a cylinder is suppressed by a weight of a user and the length of the cylinder is reduced.
Construction of a chair in which a gas cylinder of a related art is adopted, is described in detail in U.S. Pat. No. 6,199,952.
In the meantime, the construction of the gas cylinder of a related art will be briefly described in the following. The gas cylinder of a related art includes: a spindle of a cylindrical shape; a base tube of a cylindrical shape, to the inside of which the spindle is inserted; a piston whose lower end is fixed on the lower side of the base tube and inserted to the inside of the spindle. As detailed description of the gas cylinder is known by a plurality of the related arts disclosed, other details will be omitted.
With such construction, the spindle is moved up and down by external force and restoring force of gas pressure, whereby operation of the gas cylinder is performed.
But, stroke range in which the gas cylinder of the related art could move up and down, depends on the whole size of the gas cylinder in up and down directions, particularly on the size of the spindle. Therefore, in case that stroke of the gas cylinder in up and down direction should be large like the cases that a body of a user is big or a table is large, the size of the gas cylinder, particularly the size of the spindle should be larger to meet the required stroke size.
Accordingly, manufacturing costs of the gas cylinder has increased, and the gas cylinder should be designed again according to a separate specification.
Also, as separate parts for use in manufacturing the gas cylinder should be newly made, much costs has been consumed.